The QT interval of the electrocardiogram reflects ventricular myocardial repolarization, and abnormalities in the duration of the QT interval are the most common indicator of abnormal repolarization. Although a number of hypotheses exist for how abnormal repolarization, and specifically QT prolongation, results in ventricular arrhythmias, the most consistent finding appears to be that during prolonged depolarization sodium channels recover from inactivation and reactivate, causing what are termed early afterdepolarizations. When combined with heterogeneity in repolarization as well, these early afterdepolarizations create a favorable myocardial substrate for reentry, resulting in propagation of intramyocardial reentry waves and torsade de pointes5.